The present invention relates generally to an endoscopic device, and more particularly too an endoscopic device having differing mechanical properties along its length.
Endoscopic devices are medical devices use for examining and performing surgery inside a patient's body. Endoscopic devices typically include an elongate member for entering the body through a natural orifice or an incision and for extending into and through a body canal, an internal cavity or an organ so the interior of the body can be visually examined or operated upon without making large incisions in the patient. Endoscopic devices permit less invasive examination and surgeries than conventional examination and surgical methods.
It is envisioned it may be desirable for some portions of endoscopic devices to have different mechanical properties than the mechanical properties of other portions. For example, it may be desirable for a distal portion of an endoscopic device to be stiffer or less stiff than other portions of the device. More particularly, certain endoscopic devices known as endoscopic tissue manipulators or endoscopic tissue retractors may benefit from some portions of the device having different mechanical properties. As shown in U.S. Patent Application Publication No. 2005/0080435 A1, entitled, “Tissue Retractor and Method for Using the Retractor,” filed Dec. 5, 2003, endoscopic tissue retractors include a flexible shaft made from coiled wire surrounded by a heat shrinkable polymer outer sleeve and having an end cap. Hooks positioned inside the coil are extendable through the end cap. The end of the retractor is positioned adjacent tissue the operator desires to manipulate when the hooks are retracted. Then the hooks are extended through the end cap. Because the hooks move along opposite arcs as they extend, the hooks pierce the tissue and engage the tissue as they are extended to attach the end of the manipulator to the tissue. Once the hooks engage the tissue, the manipulator may be retracted or otherwise moved to manipulate the tissue into a desired position. As will be appreciated by those skilled in the art, extending the hooks causes the coil forming a portion of the outer casing to be put in tension. If the tensile loads are great enough, the end of the coil can become stretched, thereby affecting its operation. To prevent strands of the coil at the end manipulator from stretching in tension when the hooks are extended, it is desirable for the end of the coil to be stiffer in tension than the rest of the coil. Under some circumstances, it is also envisioned that it may be desirable for the distal portion of the endoscopic manipulator to be stiffer in bending than the remainder of the manipulator. In some cases, having a stiffer end portion would allow for easy movement of the manipulator within a working channel, yet provide a stiffer device when positioning the hooks and engaging tissue.
Tensile loads may also be created in other types of endoscopic equipment. For example, as will be appreciated by those skilled in the art, endoscopic scissors may have tensile loading as they are opened due to preloads within the scissors mechanism needed for the scissors to function. In addition, endoscopic stapling devices that use fasteners stored in the device in their deformed shape may have significant tensile loading caused by the restoring forces of the staples on their confinement chamber.